Contrast-enhanced ultrasound (CEUS) can sensitively show the blood perfusion characteristics of thyroid nodules, which is a useful supplement to gray-scale ultrasound. However, there is no standard combined diagnostic method of gray-scale ultrasound and CEUS. Therefore, the aim of this study was to compare the diagnostic performance of the integrated scoring method and the up-and-down scoring method. This study was a multicenter retrospective clinical study and followed the Standards for Reporting of Diagnostic Accuracy Studies (version 2015). Inclusion criteria: 1) participants with at least one thyroid nodule larger than 5 mm confirmed by conventional ultrasound; 2) participants underwent gray-scale ultrasound, contrast-enhanced ultrasound and fine needle aspiration biopsy of the thyroid nodule successively; 3) participants have a final diagnosis of benign or malignant. Exclusion criteria included: 1) participants with cytologic findings of Bethesda I, III, or IV without definitive benign or malignant pathologic findings; 2) participants with a history of thyroid fine needle aspiration, ablation or surgery; 3) participants with low quality ultrasound images (e.g., severe artifacts or low image resolution). According to the American College of Radiology Thyroid Imaging Reporting and Data System, only one thyroid nodule with the highest point was included in each participant. A total of 600 participants from January 2018 to December 2022 were consecutively included in Sun Yat-sen Memorial Hospital of Sun Yat-sen University to form a training set (average age 48 years; Range 24-81 years old). A total of 200 subjects with thyroid nodules from January 2022 to December 2022 were consecutively included to form an external validation set in Houjie Hospital of Dongguan City, Guangdong Province (mean age 46 years; Range 30-74 years). The malignant risk of enrolled thyroid nodules and the necessity of biopsy were evaluated by integrated scoring method and up-and-down scoring method, respectively. The diagnostic performance and unnecessary biopsy rate of the above two methods were calculated and compared.

Inclusion Criteria:

• Participants with thyroid nodules with a solid component ≥5 mm confirmed by conventional ultrasound;
• Participants who underwent conventional ultrasound, contrast-enhanced ultrasound, and fine-needle aspiration biopsy;
• Participants with a final benign or malignant pathological results.

Exclusion Criteria:

• Participants with cytopathology of Bethesda I, III, or IV and without final benign or malignant pathology；
• Participants with a history of thyroid ablation or surgery;
• Participants with low-quality ultrasound images.

We included patients at Sun Yat-sen Memorial Hospital (the internal validation set) and Houjie Hospital of Dongguan(the external validation set) at the same eligibility criteria described above from January 2021 to December 2022.

Data generated or analyzed during the study are available from the principal investigator by request.

The first week after the publication of the research papers.

Data generated or analyzed during the study are available from the principal investigator by request.